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With temperatures in the 70s and North Texas gardens beginning to bud, we decided not to wait until April to talk about sun education and skin cancer prevention. Every day for the next several weeks, we will write a short post on all sorts of interesting topics relating to sun damage precaution. There will even be a quiz for you to take – a question each day with the answer given the following day. We will conclude with two weeks of discounted skin checks and biopsies (if needed), specials on great sun blocks and other facial products, and a “skin” evening at the office.

(Full disclosure: many of our posts will be heavily borrowing material from SkinCancer.org – a great resource!)



Humans need vitamin D for bone growth and as an essential part of our immune system. Low levels of this important vitamin put you at high risk for osteoporosis, muscle aches and weakness, skeletal deformities, and fractures. So how does the sun play into vitamin D regulation? When your skin is exposed to sunlight (specifically ultraviolet B (UVB) rays) UVB rays interact with the skin protein 7-DHC, converting this protein to Vitamin D3, the active form of Vitamin D.

Vitamin D keeps bones strong by regulating calcium levels. Without Vitamin D, calcium absorption declines, and bones soften and weaken. The media is full of claims that Vitamin D helps to decrease heart disease and protect from heart disease, diabetes type 1, and rheumatoid arthritis. These claims are based on observational studies only, and may or may not be valid. But no one doubts maintaining a normal level of Vitamin D is important.

What is a Healthy Level of Vitamin D?

If you’re having blood drawn for your annual checkup, ask your doctor to test your vitamin D level. On your lab report, here’s what your number means.

TODAY’S QUIZ QUESTION:  Shouldn’t I spend some time outdoors without sun protection so I can maintain a healthy level of vitamin D?



Many people think using sunscreen (and other forms of sun protection) creates high risk for vitamin D deficiency. The claim is the best way to have good levels of vitamin D is through unprotected sun exposure. Dermatologists, plastic surgeons, and other skin professionals disagree with this notion, stating the risk from unprotected sun exposure outweighs the good it does with vitamin D production.

To understand these conflicting viewpoints, we need to understand the effects of sun on our skin. The sun’s UV light damages the skin’s cellular DNA, creating genetic mutations that can (but not always) lead to skin cancer. Both the World Health Organization and the US Department of Health and Human Services consider solar UV a proven human carcinogen. UV radiation is linked to 90% of non-melanoma skin cancers, 86% of melanomas, premature skin aging, cataracts, and eye/eyelid cancers. Controlled studies have shown regular use of SPF 15 or higher sunscreen reduces the chances of developing skin cancer by 40%, melanoma by 50%, and premature skin aging by 24%.  That’s why there isn’t such a thing as a “protective tan”, since tanning itself (the color change of the skin) is the result of DNA damage in the skin.

So the big question is:  If I use sunscreen regularly, will this lead to vitamin D deficiency?

The answer is not necessarily so. Studies have shown people who use daily sunscreen can maintain their vitamin D levels. Even though high SPF sunscreens filter out UVB radiation (remember UVB wavelengths trigger vitamin D production in the skin, but also are the cause of sunburn and can lead to skin cancers), in reality some UV rays will still reach your skin.  For example, SPF15 filters 93% of UVB rays, SPF 30 filters 97%, and SPF 50, 98%. But this still leaves 2 – 7% reaching your skin even if you use them perfectly. And who really does that?

ANSWER TO YESTERDAY’S QUIZ QUESTION which was: Shouldn’t I spend some time outdoors without sun protection so I can maintain a healthy level of vitamin D? 

NO. Healthy vitamin D levels are indeed important to bone health, proper immune function, and your overall health. However, there are several risk-free ways to achieve healthy vitamin D levels that don’t involve sun exposure. Seeking sun exposure without protection will only add to your cumulative sun damage, increasing your skin cancer risks, and accelerating skin aging. And don’t even think about getting vitamin D from a tanning bed! Tanning beds mainly emit UVA, while your skin only synthesizes vitamin D in response to UVB rays. A balanced diet including fortified foods such as yogurt and cereal as well as certain fatty fish along with oral supplements are health ways to achieve appropriate levels of vitamin D.

TODAY’S QUIZ QUESTION:  Since a base tan can prevent sunburn, can I reduce sun damage and skin aging by tanning?



Unprotected sun exposure of 10-15 minutes to arms, legs, abdomen, and back two to three times a week will be all your skin needs to produce all the vitamin D you need. If you produce more than you need, your body automatically disposes of it. (Remember vitamins A, K, D, and E are fat soluble, so too much is not good for you.)  So being in the sun more than this just leads to sun damage with no vitamin benefit. Unfortunately, even as little as 15 minutes of unprotected sun time a day adds up over your lifetime to increase genetic mutations and thereby increasing the risk of skin cancer.

UVA radiation (320 – 400 nanometers) are the key UV waves behind skin aging as well as a contributor to skin cancer. UVB waves (290 – 320 nm) make the skin synthesize vitamin D and also produce sunburn and skin cancers.  A 2015 study in the Journal of Science found that UVA damage to the skin’s pigment cells (melanocytes) starts in less than a minute in the sun and keeps developing for hours after sun exposure stops. Because of the rapid onset of DNA damage coupled with the harmful cumulative effects of UVA and UVB exposure, one can protect the skin the best by using both SPF 15+ broad-spectrum sunscreen (UVA and UVB protection) and wearing sun protective clothing, hats, and sunscreens.

What about using a tanning booth as a vitamin D source? That just doesn’t make sense as the rays used are mostly UVA, so you get damage, skin cancer potential, and no vitamin D production.

ANSWER TO YESTERDAY’S QUIZ QUESTION which was:  Since a base tan can prevent sunburn, can I reduce sun damage and skin aging by tanning?

NO. That’s a big myth! People come into my office with a tan, saying it’s a “base tan” and it makes them feel protected, but tanning occurs because you’ve already injured your skin. It’s the skin’s imperfect attempt to prevent further harm by putting up a darker wall of pigment. Whether outdoors or in a tanning bed, UV radiation damages the skin’s DNA, which accelerates skin again and increases the risk of skin cancer. It’s very hard to reverse the damage. Here’s my mandate: with or without sunscreen, never lie out in the sun to try to get a tan, and don’t use tanning beds. There’s no such thing as a protective or base tan!

TODAY’S QUIZ QUESTION:  Can the sun age my skin before its time?




  • fatty fish such as salmon (wild salmon has almost 1,000 IU [international units] of vitamin D per 3.5 oz), ahi tuna, and mackerel
  • beef liver, cheese, and egg yolks
  • fortified foods: read the labels on milk and orange juice; be cautious with orange juice due to high sugar concentrations


  • The recommended daily allowance is 600 IU for ages 1 – 70, 400 IU for children under one year, and 800 IU for those over 70.
  • An old fashioned remedy is cod liver oil at 1,360 IU per tablespoon.
  • An easy alternative is to use one of the many over-the-counter supplements available such as Replesta. However, be sure to keep supplementation below 2,000 IU per day. Dosage above that level can lead to toxicity and excess calcium in the blood and kidneys.

Bottom line – food, supplements, and usual incidental protected sun exposure will give you all the vitamin D you need!

ANSWER TO YESTERDAY’S QUIZ QUESTION which was:  Can the sun age my skin before its time?

YES. So much of what we think of as “natural” aging isn’t natural at all. It’s damage from the sun. In fact, the sun’s harmful ultraviolet (UV) rays cause about 90 percent of the visible signs of skin aging. Skin changes attributable to the sun, including dark spots, enlarged blood vessels, sagging, leathery texture and wrinkles, are called photodamage.

TODAY’S QUIZ QUESTION: Can sunscreen help prevent skin aging?



There is strong evidence sun exposure and sunburns during childhood multiply the risk of one day developing skin cancer, including melanoma. A recent study showed many parents actively exposed their infants to sun each day, mistakenly believing this would build up a tolerance to the sun’s rays. But the skin of all infants – not just the fair skinned – is particularly vulnerable to sun damage as they have not developed all the melanin they will have as adults. Melanin is the natural skin pigment that provides some protection against damaging radiation. (More on that in a later post.)

How to Protect Your Baby’s Skin (Under Six Months of Age)

An infant’s skin is so sensitive, it is best not to apply sunscreen at this age. Instead, shield the baby from the sun by avoiding direct sun exposure and dressing her in brimmed hats and lightweight clothing that covers arms and legs.

Other tips:

  • Avoid walks outside between 10:00 a.m. and 4:00 p.m.
  • Keep to the shady side of the street
  • Use the sun shield on the stroller
  • Use baby sunglasses that filter UV rays with soft strap to keep in place (VERY important as the melanin in babies’ eyes is still forming)
  • Protect from UVA/UVB rays during car rides with a UV shield over the window

Children of color also need protection. Even though darker skin is more protective due to more melanin, the density of melanin is less in infants and toddlers than in adults.

ANSWER TO YESTERDAY’S QUIZ QUESTION which was: Can sunscreen help prevent skin aging?

YES.  In 2013 an important study finally proved what many of us have long suspected. It showed people who used an SPF 15 or higher broad-spectrum sunscreen every day had almost no detectable skin aging over four and a half years, while those who did not use sunscreen every day did show skin aging.

The key is to apply sunscreen all year long no matter what. You don’t have to feel warmth to be exposed to ultraviolet A (UVA) radiation. While UVB rays are strongest in summer months, UVA rays are intense year-round – they inflict damage on your skin in cold weather, at high altitude, through clouds and fog, and even through glass. That’s why people in the U.S. tend to have more skin aging (and skin cancer) on the left side, due to exposure through the car window. It’s the opposite in countries where the driver sits on the right.

TODAY’S QUIZ QUESTION:  I’ve heard most sun damage occurs before age 18, so can’t I just stop worrying about my skin?


NO. Contrary to popular belief, you will get about 80% of your lifetime sun damage after age 18. Sun protection at any age can slow the advance of skin aging. Daily sun protection for life can make all the difference.

Dr. Kerner, Plastic & Reconstructive Surgery
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